F reezing is better than heat therapy for tiny kidney tumours

Cryoablation, which kills cancer by freezing it, results in a lower risk of cancer-related death than heat-based thermal ablation for patients with early-stage renal cell carcinomas (RCCs) measuring 3 to 4 centimetres, according to a preliminary study published in The Journal of Urology, an Official Journal of the American Urological Association (AUA). The journal is published by Wolters Kluwer as a part of the Lippincott catalogue.

“In contrast, for patients with RCCs smaller than 3 centimetres, either cold-based or heat-based therapy is just as effective in reducing cancer-specific mortality,” comments lead author Gabriele Sorce, MD, of IRCCS San Raffaele Scientific Institute, Milan. “The findings may help us to better tailor the choice of ablation technique for patients with small RCCs.” Cryoablation has a lower risk of cancer death than heating.

Renal cell carcinoma is the form of kidney cancer that occurs most frequently. Frozen or heated tumours are becoming a more popular form of treatment for individuals with RCCs in the early stages that are under 4 cm in size.

For individuals with clinical stage T1a RCCs, ablation, a cancer-killing treatment, can offer good survival rates without requiring more extensive kidney surgery.

However, for a subset of patients with clinical stage T1a RCCs and tumours between 3 and 4 cm in size, ablation appeared to be “less helpful.” Current European recommendations favour cryoablation over heat-based thermal ablation for malignant tumours measuring 3 to 4 cm, however US standards allow either procedure to be used.

For T1a RCCs sized 3 cm or less, either freezing or heating is permitted, according to both sets of recommendations. Between 2004 and 2018, a multidisciplinary research team studied individuals with stage T1a RCCs who had been frozen or heated. The Surveillance, Epidemiology and End Results (SEER) Program of the National Cancer Institute in the United States served as the source of the patients. Two matched patient groups with tumours measuring 3 to 4 cm in size were the subject of the study: 757 had cryoablation, and 388 underwent thermal ablation using heat.

The average age was 71 at the start of treatment. Follow-up information on cancer-specific mortality, or the likelihood of dying from kidney cancer alone, was available for 422 patients treated with freezing and for 238 patients treated with heating.

Those with RCCs measuring 3 to 4 cm who had cryoablation had an estimated cancer-specific death rate of 8.5%, compared to 12.9% for those who underwent heat-based thermal ablation, eight years after therapy. About 40% of patients in both situations passed away from diseases other than cancer.

Treatment options for kidney tumours that are tiny and potentially curative
After adjusting for non-cancer-related mortality and other covariates, patients who had heat-based thermal ablation for RCCs between 3 and 4 cm were twice as likely to pass away from kidney cancer. The anticipated cancer-specific mortality, however, was comparable between groups for individuals with tumours less than 3 cm in size: 6.8% after cryoablation and 6.1% after heat-based thermal ablation.

In patients with stage T1a RCCs sized between 3 and 4 cm, the research is one of the first to evaluate clinical results directly between freezing and heating. The findings imply that when compared to cryoablation, heat-based thermal ablation has “a very statistically significant and clinically important” disadvantage with regard to the long-term risk of kidney cancer mortality.

“Conversely, in patients with tumour size 3 centimetres or smaller, either ablation technique is equally valid,” says Dr Sorce. “We believe our findings have important implications for clinical decision-making and informed consent for patients with these small, potentially curable kidney cancers”